This invention relates to a method for automatically adjusting an adjustable headrest of a motor vehicle seat and to a device for carrying out said method.
In connection with an increase of the passive safety inside a motor vehicle, the headrests mounted on motor vehicle seats make an essential contribution. They serve to absorb acceleration forces which act on the head of a passenger in a case of crash. To be able to provide an optimum protection, the headrests must be adjusted to the respective passenger and his stature such that they contact the head of the passenger approximately at the level of the ears. A headrest making contact too high or too low on the other hand increases the risk of injury in a case of crash. For this reason, height-adjustable and tiltable headrests are widely known from the prior art, which allow an adjustment of the headrest by the passenger.
An automation of the height adjustment of the headrests is also known from the prior art. In DE 37 30 210 A1, for example, a device for height adjustment of a headrest is described, which provides for an individual adaptation by means of a sensor array detecting the head height.
The person occupying the vehicle seat associated to the headrest, however, should still touch the headrest with his head or neck even at the lowest height position of the headrest. Furthermore, the described invention only is intended for a one-time adjustment, i.e. to be made before start of the drive, which moreover does not take into account whether the vehicle seat is occupied by a person or an object.
DE 44 33 601 C1 describes a method and a device for activating or deactivating safety-relevant systems inside the passenger cell of a motor vehicle. Among other things, a sensor means is described, which is focused on the head region of the motor vehicle seat, so as to detect an occupation by a passenger. Beside the specific adaptation to the passenger or his seating position, the activation or deactivation of further safety means, such as airbags, furthermore is controlled therewith. What remains disadvantageous in this invention on the one hand is the person-related adjustment of the headrest, which always requires a measurement of the seat occupation for a position adjustment. On the other hand, only the lowermost adjustment position of the headrest will be moved to in the case of a non-detected seat occupation. In this position, however, the headrest normally will increase the risk of injury for a passenger, when the occupation has been detected erroneously.